Finding the best sequence in flexible and stiff composite laminates interleaved by nanofibers

2019 ◽  
Vol 53 (28-30) ◽  
pp. 4065-4076 ◽  
Author(s):  
Hamed Saghafi ◽  
Seyed R Ghaffarian ◽  
Hesam Yademellat ◽  
Hossein Heidary
Keyword(s):  
Composite Laminates ◽  
The Other ◽  
Mode I ◽  
Mode Ii ◽  
Impact Point ◽  
Damage Pattern ◽  
Mode Ii Fracture ◽  
Numerical Studies ◽  
Other Hand ◽  
Fracture Tests

The brittle nature of thermoset-based composite laminates restricts the application of these materials in various industries. One of the most effective methods for resolving this problem is interleaving the laminate by nanofibrous mats. Applying nanofibers between all layers is very costly and time-consuming. Therefore, the efficiency of using nanofibers in half of the layers for various interleaf sequences is investigated in this study. On the other hand, since the damage pattern is different in thick and thin laminates under impact, its effect is also considered. Cohesive parameters are required for impact modeling in ABAQUS, so they were obtained by mode-I and mode-II fracture tests and numerical studies. The results showed that the best position for interleaving the nanofibers is mid-layers and top layers (near impact point) in thin (flexible) and thick (stiff) laminates, respectively. If it is not possible to predict the damage penetration through the thickness, putting nanofibers in the top section of the laminate is suggested.

scholarly journals Comparison of Tensile Strength and Fracture Toughness of Co-Bonded and Cold-Bonded Carbon Fiber Laminate-Aluminum Adhesive Joints

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3778
Author(s):  
Fabrizio Moroni ◽  
Alessandro Pirondi ◽  
Chiara Pernechele ◽  
Luca Vescovi
Keyword(s):  
Fracture Toughness ◽  
Tensile Strength ◽  
Carbon Fiber ◽  
Adhesive Joint ◽  
Mode I ◽  
Mode Ii ◽  
Mode Ii Fracture ◽  
Fracture Tests ◽  
Peel Stress ◽  
Cold Bonding

The purpose of this work is to compare the co-bonding vs. cold-bonding route on the adhesive joint performance of a CFRP (Carbon Fiber Reinforced Polymer) laminate–aluminum connection. In particular, the overlap shear, tensile strength and Mode I and Mode II fracture toughness will be evaluated. The adhesives for co-bonding and cold-bonding are, respectively, a thermosetting modified epoxy, unsupported structural film and a two-component epoxy adhesive, chosen as representative of applications in the high-performance/race car field. The emerging trend is that, in tensile e Mode I fracture tests, the failure path is predominantly in the composite. Mode II fracture tests instead resulted in a cohesive fracture, meaning that, under pure shear loading, the weakest link may not be the composite. The lap-shear tests are placed midway (cohesive failure for co-bonding and composite delamination for cold-bonding, respectively), probably due to the different peel stress values related to the different adhesive Young’s modulus. The exploitation of the full capacity of the adhesive joint, hence the possibility of highlighting better, different performances of co-bonding vs. cold-bonding, would require consistent improvement of the out-of-plane strength of the CFRP laminate and/or to someway redistribute the peel stress on the bondline.

Seawater effects on interlaminar fracture toughness of glass fiber/epoxy laminates modified with multiwall carbon nanotubes

2020 ◽  
pp. 002199832095078
Author(s):  
Julio A Rodríguez-González ◽  
Carlos Rubio-González
Keyword(s):  
Carbon Nanotubes ◽  
Fracture Toughness ◽  
Glass Fiber ◽  
Composite Laminates ◽  
Multiwall Carbon Nanotubes ◽  
Mode I ◽  
Mode Ii ◽  
Interlaminar Fracture Toughness ◽  
Multiscale Composite ◽  
Multiwall Carbon

In this work, the effect of seawater ageing on mode I and mode II interlaminar fracture toughness ([Formula: see text] and [Formula: see text]) of prepreg-based woven glass fiber/epoxy laminates with and without multiwall carbon nanotubes (MWCNTs) has been investigated. The first part of the investigation reports the moisture absorption behavior of multiscale composite laminates exposed to seawater ageing for ∼3912 h at 70 °C. Then, the results of mode I and mode II fracture tests are presented and a comparison of [Formula: see text] and [Formula: see text] for each type of material group and condition is made. Experimental results showed the significant effect of seawater ageing on [Formula: see text] of multiscale composite laminates due to matrix plasticization and fiber bridging. The improvement in [Formula: see text] of the wet glass fiber/epoxy laminate was about 50% higher than that of the neat laminate (without MWCNTs) under dry condition. It was also found that the presence of MWCNTs into composite laminates promotes a moderate increase (8%) in their [Formula: see text] as a result of the additional toughening mechanisms induced by CNTs during the delamination process. Scanning electron microscopy analysis conducted on fracture surface of specimens reveals the transition from brittle (smooth surface) to ductile (rough surface) in the morphology of composite laminates due to the influence of seawater ageing on the polymeric matrix and fiber/matrix interface.

scholarly journals The influence of interlayer/epoxy adhesion on the mode-I and mode-II fracture response of carbon fibre/epoxy composites interleaved with thermoplastic veils

2020 ◽  
Vol 192 ◽  
pp. 108781 ◽  
Author(s):  
Dong Quan ◽  
Brian Deegan ◽  
René Alderliesten ◽  
Clemens Dransfeld ◽  
Neal Murphy ◽  
...  
Keyword(s):  
Carbon Fibre ◽  
Epoxy Composites ◽  
Mode I ◽  
Mode Ii ◽  
Mode Ii Fracture
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